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CONCLUSION

Malware which utilizes connect-back (aka call-home) features poses a significant threat to networks of all sizes and shapes. Simple inbound filtering or NAT is inappropriately relied upon in many cases to "secure" a network. The malware described in this paper is just one example of an active criminal network leveraging this technique to allow arbitrary inbound connectivity through a filtering or NAT device. The authors are aware of several other criminal networks utilizing these techniques and success breeds imitation.